INTERACTION BETWEEN POLY-3-HYDROXYBUTYRATE-CO-3-HYDROXYVALERATE AND ADENITRIFYING PSEUDOMONAS STRAIN

In a laboratory-scale system, denitrification activity of a heterotrop hic microbial starter culture changed when different lots of poly-3-hy droxybutyrate-co-3-hydroxyvalerate (P(HB-co-HV)) were used as the soli d carbon source in the heterotrophic denitrification reactor. In this study, possible influences of physical and chemical properties of comm ercially produced P(HB-co-HV) (Biopol(R)) on biofilm formation and met abolic activity of a denitrifying starter culture were investigated. T hese parameters indicate the polymers' suitability for the application as the matrix substance in the bioreactor. No differences in microstr ucture were detected between the different lots of polymers. Growth in hibitory effects by chemical additives were found in the case of triac etine, which was included as a plasticizer in seven of eight tested lo ts. The amount of hydroxyvaleric acid in the polymer was not assumed t o affect denitrification activity. Relevant differences could be detec ted regarding primary adhesion of the starter culture Pseudomonas sp. strain 2nIII. It showed good adsorption properties to hydrophobic subs tances with a dependence on precultivation conditions. Pseudomonas sp. strain 2nIII degraded poly-3-hydroxybutyrate acid homopolymer and P(H B-co-HV) copolymers but was unable to break up poly-3-hydroxyvaleric a cid. A possible reason for these findings is the substrate specifity o f the polyhydroxyalkanoate depolymerase.